Generally, a personal digital assistant (PDA) has a touch panel such as a touch screen or a touch electrode pad installed therein, due to better use of a space and use convenience.
A touch panel may be broadly divided into a capacitive overlay type, a resistive overlay type, an infrared beam type, a surface acoustic wave type, etc. Recently, a capacitive overlay type touch panel has come into the spotlight.
Recently, according to the needs of consumers, various attempts to integrate a touch sensor have been made in order to realize a slim, lightweight and bezel-less touch panel. For reference, a method of integrating a touch sensor may be roughly divided into an in-cell method and an on-cell method according to an object (a display panel or cover glass) with which the touch sensor is integrated. As one in-cell method, advanced in-cell touch (AIT) technology refers to touch technology of installing a touch sensor in a liquid crystal display (LCD) cell, can provide superior touch sensitivity, and can decrease a panel thickness and a bezel width to implement slimness. Therefore, this technology has been widely used.
Recently, technology of sensing touch input even in a state in which a display is in a deactivation mode (sleep mode) to control the function of a terminal was proposed according to the needs for a new user interface.
However, in order to sense touch input in a state in which the display is in the deactivation mode, the touch panel is continuously scanned to confirm external touch even in the deactivation state of the display. Accordingly, the internal computational burden of a touch controller increases and a response speed decreases, thereby increasing power consumption.
Therefore, recently, various researches into reducing power consumption and improving response speed and accuracy of external touch have been conducted, but results have been insufficient, and thus development thereof is required.